1. Field of the Invention
The present invention relates to the field of intelligent transceivers such as set-top boxes, in particular bi-directional set-top boxes. More specifically, the present invention pertains to a modular set-top box architecture in which the devices needed for bi-directional communication are substantially located in a single functional block.
2. Background Art
Digital broadcast systems include direct broadcast digital satellite systems, interactive World Wide Web access systems, and digital cable systems. Digital broadcasting provides a number of advantages to subscribers, such as variety and flexibility of programming, useful and comprehensive support services (such as detailed electronic programming guides), and superior audio and video quality. Subscribers receive broadcast digital signals via set-top boxes or other similar consumer electronic equipment (generally, a xe2x80x9ctransceiverxe2x80x9d) located in the subscriber""s home. In an intelligent set-top box, information and instructions associated with receiving and processing digital broadcast signals are stored in a memory unit of the set-top box and executed by a processor. With a bi-directional set-top box, in addition to receiving broadcast signals, a subscriber can transmit messages to the digital broadcast system operator (also referred to as a Multiple System Operator, MSO).
Using a bi-directional set-top box, a subscriber can select a premium service offered by the MSO, such as a pay-per-view event or movie, and the subscriber""s selection as well as information needed for billing purposes are transmitted to the MSO. In a common implementation, a xe2x80x9csmart cardxe2x80x9d stores the information needed for billing, and on a periodic basis (perhaps once per month) an automatic connection is made between the transceiver and the MSO so that the billing information can be transmitted to the MSO. To prevent unauthorized use, MSOs typically broadcast a scrambled signal. The signal is descrambled in the transceiver using a xe2x80x9cscramble keyxe2x80x9d provided by the MSO.
A set-top box performs a number of functions associated with processing a broadcast digital signal. In a typical prior art embodiment, the digital signal received by the set-top box is scrambled, and the signal is descrambled by the set-top box before further processing occurs. The descrambled signal is then encrypted within the set-top box in order to prevent unauthorized duplication and use (xe2x80x9cpiratingxe2x80x9d) of the descrambled signal. Once the encrypted signal is at a more secure location within the set-top box, it is decrypted for further processing. The digital signal is typically in a compressed data format such as MPEG (Moving Picture Experts Group) for video signals and/or Dolby AC3 for audio signals, and so the decrypted signal is decoded (uncompressed) by the set-top box. After decoding, the audio content and video content contained in the digital signal are processed so that it can be viewed and/or listened to by the subscriber using, for example, a television set.
Prior Art FIG. 1 is an illustration of the various frequencies associated with different types of broadcast signals. The frequencies in the range of approximately 5-42 MHz are known as xe2x80x9cupstreamxe2x80x9d signals, and the frequencies in the range of approximately 54-860 MHz are known as xe2x80x9cdownstreamxe2x80x9d signals. From the perspective of a set-top box, an upstream signal is transmitted and a downstream signal is received.
Within the upstream range, the range of frequencies from approximately 5-26 MHz are known as xe2x80x9cout-of-band (OOB) upstream,xe2x80x9d and the range of signals from approximately 26-42 MHz are known as xe2x80x9ccable modem upstream.xe2x80x9d Within the downstream range, the range of frequencies from approximately 70-130 MHz are known as xe2x80x9cout-of-band downstream.xe2x80x9d
The OOB upstream range is used by the set-top box to send billing information, for example, to the broadcast system operator or MSO. The cable modem upstream range is used by the set-top box for communicating with the World Wide Web, for sending e-mail, and the like. The in-band downstream range is used by the set-top box for receiving audio and video content. The OOB downstream range is used by the set-top box for receiving service information (e.g., electronic programming guide information, EPG) and for receiving the scramble key used by the set-top box to descramble a scrambled broadcast digital signal. An EPG typically provides information such as the names of programs, the time and channel associated with each program, and extended text tables with information regarding the subject matter of the program, actors names, and the like. An EPG generally is formatted as a table, with channels along one axis of the table, times along the other axis, and the name of the program at the intersection of the time and channel.
Current broadcast systems typically need to support both analog and digital television, and so the in-band downstream range is used for carrying both analog and digital audio and video (A/V) content. However, the bandwidth of the in-band downstream range is too narrow to accommodate the service information and scramble key in addition to the analog and digital A/V content. As a result, the OOB downstream range is used to carry the service information and scramble key.
Prior Art FIG. 2 is a block diagram showing the architecture of a typical broadcast system 200. A/V content for broadcast system 200 is provided by A/V content provider 230. The A/V content is provided in the in-band downstream range to the many set-top boxes in broadcast system 200 (e.g., set-top boxes 250a, 250b, 250c, 250d and 250e). Depending on the type of system, broadcast system 200 may utilize a terrestrial broadcast (e.g., a wireless broadcast) or a terrestrial line (e.g., cable).
EPG server 210 provides the service information and scramble key for broadcast system 200, although there may be a different source for this information in other implementations. The service information and scramble key are forwarded to out-of-band modulator 220 and then broadcast in the OOB downstream range to set-top boxes 250a, 250b, 250c, 250d and 250e. 
Set-top boxes 250a, 250b, 250c, 250d and 250e may also be communicatively coupled to the Internet via Internet router 240. Communication with the Internet typically uses Internet Protocol (IP).
Prior Art FIG. 3 is a block diagram illustrating an exemplary embodiment of an intelligent transceiver (e.g., set-top box 250a) used in broadcast system 200 of FIG. 2. Central processing unit (CPU) 330 contains a processor and memory (not shown) for processing information and instructions used by set-top box 250a. 
With reference to FIG. 2 and FIG. 3, set-top box 250a includes an in-band tuner 305 for receiving the in-band downstream signals from A/V content provider 230. In-band tuner 305 typically receives fixed frequency broadcast channels. The in-band downstream signal is demodulated by demodulator 310, then forwarded to A/V decoder 315 for decoding, as described above. From A/V decoder 315, the decoded signal is sent to a graphics block (not shown) for processing so that it can be displayed and/or listened to.
Continuing with reference to FIG. 2 and FIG. 3, set-top box 250a also includes an out-of-band tuner 320 for receiving the out-of-band downstream signal containing the scramble key and service information (SI). The out-of-band downstream signal is demodulated by modulator/demodulator 325. The scramble key can be applied to the in-band downstream signal to descramble that signal and retrieve the A/V content (when the in-band downstream signal is scrambled, e.g., for a pay-per-view movie or event). The service information (if compressed) is decoded by A/V decoder 315, then sent to a graphics block for processing so that the electronic programming guide can be displayed. Messages from set-top box 250a, such as a selection of a pay-per-view movie or event and the associated billing information, is modulated using modulator/demodulator 325 and sent to the MSO in the out-of-band upstream range.
Set-top box 250a further includes cable modem 340 to receive the IP data signals (e.g., data packets) retrieved from the Internet and also to send IP data signals to the Internet, including electronic mail. Cable modem 340 typically can also receive in-band signals for non-broadcast information (e.g., variable frequency broadcast channels controlled by the MSO).
A disadvantage of broadcast system 200 is that it requires the use of in-band signals, out-of-band signals, and IP signals in order to send A/V content, service information, a scramble key, electronic mail, etc. Accordingly, it is necessary for a set-top box (e.g., set-top box 250) to include an in-band tuner 305, an out-of-band tuner 320, and a cable modem 340. As a result, additional complexity is introduced into broadcast system 200 and set-top box 250. Consequently, manufacturers of set-top boxes face increased development and fabrication costs, and MSOs face higher costs associated with running and maintaining a broadcast system. These costs are reflected in the prices charged to consumers. Clearly, for the benefit of the manufacturer and the MSO as well as the consumer, it is desirable to minimize these costs.
Accordingly, what is needed is an apparatus and/or method that can reduce the costs of a set-top box and a broadcast system, in particular with regard to supporting the use of in-band signals, out-of-band signals and Internet Protocol (IP) data packets. What is also needed is an apparatus and/or method that can address the above need and that can continue to provide the audio/video content, service information, scramble key, and Internet access currently provided by the in-band signals, out-of-band signals and Internet Protocol data packets.
The present invention includes an apparatus and method thereof that satisfy the above needs. These and other advantages of the present invention not specifically mentioned above will become clear within discussions of the present invention presented herein.
The present invention pertains to an apparatus and method thereof for communicating a scramble key (for descrambling scrambled digital signals) and service information (such as that used in an electronic programming guide) to an intelligent transceiver (e.g., a set-top box) using a bi-directional digital broadcasting system (e.g., satellite systems, interactive World Wide Web access systems, and digital cable systems). The intelligent transceiver includes an in-band tuner adapted to receive from the digital broadcast system in-band digital signals comprising audio content and video content. The intelligent transceiver also includes a second tuner adapted to receive a scramble key over the World Wide Web via a cable modem.
In one embodiment, the in-band digital signals received by the in-band tuner also contain service information (including electronic programming guide information). In another embodiment, the digital signals received by the second tuner via the cable modem also contain service information (including electronic programming guide information). Thus, the scramble key is sent over the World Wide Web and is received by the intelligent transceiver using a cable modem. The service information (including electronic programming guide information) is sent either with the in-band signal or over the World Wide Web and is received via the in-band tuner or the cable modem, respectively.
In one embodiment, the digital signals sent over the World Wide Web are communicated using Internet Protocol.
In another embodiment, an authentication signal is sent via the cable modem to indicate that a valid intelligent transceiver authorized to receive the scramble key is connected to the digital broadcast system.
In yet another embodiment, billing information (pertaining to a subscriber""s use of a premium service such as a pay-per-view movie or event, for example) is sent via the cable modem to the digital broadcast system operator. The cable modem can also be used for Internet access and to send and receive electronic mail.
Therefore, in accordance with the present invention, it is not necessary for the broadcast system to use out-of-band signals to send service information and a scramble key. Consequently, the intelligent transceiver does not require an out-of-band tuner and demodulator to receive the service information and scramble key, and so these devices can be omitted from the intelligent transceiver. As a result, broadcast systems can be simplified, thereby reducing costs. In addition, the manufacture of the intelligent transceiver is facilitated and the cost of the intelligent transceiver can be reduced.